It sounds like you want an analog preamp with a pair of preamp output jacks and power amp input jacks on the rear panel, plus a tape monitor loop that will allow you to insert a surround processor. This configuration is available on a number of preamps, but perhaps not in the under $1k price range. There are obviously a variety of preamps you can consider, but based on your budget I'd urge you to consider the Adcom GFP-750, which can be often purchased used for about $750-800. I am not sure, however, if this preamp has the necessary rear panel configuration and tape loop monitor, but you can probably get more info from the Adcom web site, or from owners who post here.

The one I settled on for those requirements was the VTL TL 2.5. (New around $1.5k, used for $8-900-ish). Gives you a nice little tube preamp with both a processor loop and a tape loop. Oops, re-read the post, and the VTL is single ended.

If all you're basically looking to do is integrate a 2-channel system with a HT system, all you really need is a HT processor or receiver with preouts for the main channels and any old preamp to suit your tastes. You then run the center and surrounds off of the HT setup as normal and merely run the preouts from the processor into any old input on the 2-channel preamp. If you have a tape loop or a processor loop on the preamp (which are electronically the same thing by different names) you can run into the preamp there, but you don't really need it -- all it does is make operation simpler by bypassing the volume control on the preamp and running straight through onto the amp for the main speakers.

If, on the other hand, you are running into the preamp at another input (we'll pick the AUX), then the main's signal from the processor will be running through the volume control of the processor (which is what you want) and the preamp (which is extra). To compensate for this, you'd have to set the volume on the preamp to some benchmark of your choosing (preferably zero gain, if you know where that is) and then balance the channels at the processor from there. Running through both volume controls will possibly cost you a slight bit in fidelity and adds the extra step of having to police the volume on the preamp (especially when you switch back to two-channel, so as to not treat yourself to a nasty surprise), but is otherwise a perfectly viable way of integrating the two systems.

I started with the VTL pre, with both a tape loop and a HT processor loop, and it was simple and easy. Then I switched to a Rogue, which has a tape loop but not a processor loop, and ran my HT processor into the AUX. While the pre was actually at Rogue (for other reasons) I talked them about installing a HT processor loop. He said he'd be happy to do it (for fairly cheap) but that he really didn't see the point or think that it was worth while--so I didn't bother. Now I'm running a Plinius pre (an electronically upgraded CD-LAD Mk.1, but without the processor loop hardware included on the Mk.2 frame) and am running the HT mains in through the Line 2 input. Now, this would normally be perfect but for the fact that the remote control frequency for my HT receiver (Marantz) and the Plinus's volume control are apparently the same (damn, damn, damn) so that every time I want to conrol the volume of the HT reciever it ALSO changes the volume of the Plinius, thus throwing it off of the benchmark and ruining the channel balancing of the Marantz. This is basically the ONLY reason I can think of not to have a processor loop, it is exceptionally unlikely, and, wouldn't you know it, exactly what happened to me.

To conclude my ramble, you could make due with any old balanced preamp you liked the sound of--the convenience of a processor loop, while a preference of some, is by no means a necessity. A processor (or tape) loop under $1k (used) should be easily doable. Balanced plus a processor loop under $1k may be a lot harder. Depends on which you prefer. But, I guess I'm just trying to explain (however inartfully and long-windedly) that you may not need both--above all, pick the preamp you like best based on its sound, the integration issue will be doable. Best of luck.

Sdcampbell, I'm not sure I would want power amp inputs in back. Did you mean outputs?

Basically, I’d like to take the outputs for the two front channels, coming from the processor to the amp, and insert the pre. If I understand this correctly, the pre with the HT-pass thru capability would allow the signal coming from the processor to pass straight through (as untainted as possible), as though it weren't there, on its way to the amp. The second set of inputs to the pre would be connected to the outs of my Transport/DAC set up. That way, when I want to listen to 2-channel audio, I would essentially have a pure 2-channel set up: The outputs from the pre, would go straight to the amp as in any high-end rig. Right?

Kr4, I'll definitely look into the SF Line-1.

Ultimately, what I want is a good pre with this capability... because it's not like the processor can't play 2-channel - just not as well as a good pre.

I use the Adcom GFP750 for exactly this purpose. It has a HT bypass, and I have it hooked up just that way - the DAC goes right to the CD input, and the processor goes to the processor input, which goes right to the amp output without the Adcom doing anything to the signal. It works perfectly, and I gotta add, the Adcom is a killer at that price range. It's the cheapest thing in the system and it keeps up with everything else in the 2-channel (Theta, Bryston, Snell) just great. Used on Agon for 7 or 8 hundred all the time. But whichever preamp you go with, I found exactly what you suspect, even great processors (like the Cassanova) can't keep up with a (much cheaper!) good pre-amp. The HT bypass is the simplest way to go.